Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in the PKD1 or PKD2 genes and is the leading genetic kidney disease worldwide. ADPKD is characterized by overproliferation of renal cells, cyst formation, and enlargement of both kidneys that result in kidney failure. Despite the tremendous need, the one drug available for ADPKD, tolvaptan, has modest benefits and only 5% of the drug reaches the kidney. Thus, off-target side effects include hepatotoxicity and results in a quarter of ADPKD patients discontinuing the drug. As such, new therapeutic strategies that can address both efficacy and safety are urgently needed in ADPKD. To that end, the goal of this proposal is to develop urinary extracellular vesicles (uEVs) as a novel therapy for ADPKD. uEVs are inherently biocompatible, carry functional polycystin-1 (PC1) and polycystin-2 (PC2), the gene products of PKD1 and PKD2, respectively, and can supplement these defective or missing proteins in ADPKD. Additionally, uEVs naturally home to injured kidneys and are isolated from discarded urine; thus, uEV production and scale-up is feasible, noninvasive, cheap and can be made highly accessible to ADPKD patients. Specifically, in Aim 1, we will isolate and characterize the nanoparticle properties and protein and mRNA cargo in uEVs. Then we will assess uEV rescue of PC1 and PC2 in renal cells. In Aim 2, we will evaluate the pharmacokinetic properties, safety, and therapeutic properties of uEVs in a mouse model of ADPKD. Given our compelling preliminary data and the expertise of our strong collaborative team spanning nanomedicine (Chung, Viterbi) and nephrology, (Hallows, Keck), we are uniquely qualified to successfully drive this new area of research towards patient use. Our results will lay the groundwork for developing uEVs as a therapeutic strategy broadly across renal diseases.